Print head for additive manufacturing system

ABSTRACT

A print head is disclosed for use with an additive manufacturing system. The print head may include a nozzle configured to discharge a composite material. The print head may also include a source of tint configured to apply the tint to the composite material.

RELATED APPLICATIONS

This application is based on and claims the benefit of priority from U.S. Provisional Application No. 62/526,448 that was filed on Jun. 29, 2017, the contents of which are expressly incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to a print head and, more particularly, to a print head for use in an additive manufacturing system.

BACKGROUND

Continuous fiber 3D printing (a.k.a., CF3D™) involves the use of continuous fibers embedded within a matrix discharging from a moveable print head. The matrix can be a traditional thermoplastic, a powdered metal, a liquid resin (e.g., a UV curable and/or two-part resin), or a combination of any of these and other known matrixes. Upon exiting the print head, a cure enhancer (e.g., a UV light, an ultrasonic emitter, a heat source, a catalyst supply, etc.) is activated to initiate and/or complete curing of the matrix. This curing occurs almost immediately, allowing for unsupported structures to be fabricated in free space. When fibers, particularly continuous fibers, are embedded within the structure, a strength of the structure may be multiplied beyond the matrix-dependent strength. An example of this technology is disclosed in U.S. Pat. No. 9,511,543 that issued to Tyler on Dec. 6, 2016 (“the '543 patent”).

Although CF3D™ provides for increased strength, compared to manufacturing processes that do not utilize continuous fiber reinforcement, it may be helpful in some instances to affect an appearance of the discharged material. For example, it may be helpful to integrate a template (e.g., an assembly template, a drill template, etc.), instructions, and/or graphics into the discharged material. The disclosed print head is uniquely configured to provide this additional functionality and/or to address other issues of the prior art.

SUMMARY

In one aspect, the present disclosure is directed to a print head for an additive manufacturing system. The print head may include a nozzle configured to discharge a composite material. The print head may also include a source of tint configured to apply the tint to the composite material.

In another aspect, the present disclosure is directed to another print head for an additive manufacturing system. This print head may include a matrix reservoir, and a nozzle fluidly connected to the matrix reservoir and configured to discharge a composite material. The composite material may include a reinforcement at least partially coated in a matrix from the matrix reservoir. The print head may also include a cure enhancer mounted at a trailing side of the nozzle and configured to expose the matrix to a cure energy after discharge from the nozzle, and a source of tint mounted at a trailing side of the nozzle to tint the composite material after discharge from the nozzle.

In yet another aspect, the present disclosure is directed to an additive manufacturing system. The additive manufacturing system may include a moveable support, and a print head connected to the moveable support. The print head may be configured to discharge a composite material including a continuous reinforcement that is at least partially coated with a matrix. The print head may include a matrix reservoir, a nozzle configured to discharge a composite material, and a source of tint configured to apply the tint to the composite material. The print head may also include a cure enhancer configured to expose the composite material to a cure energy after discharge from the nozzle. The additive manufacturing system may also include a controller configured to coordinate operation of the moveable support with activation of the source of tint and the cure enhancer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of an exemplary disclosed additive manufacturing system; and

FIGS. 2 and 3 are diagrammatic illustrations of exemplary disclosed print heads that may be utilized with the additive manufacturing system of FIG. 1; and

FIG. 4 is an isometric illustration of an exemplary disclosed structure that may be fabricated via the additive manufacturing system of FIG. 1.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary system 10, which may be used to continuously manufacture a composite structure 12 having any desired cross-sectional shape (e.g., circular, ellipsoidal, polygonal, etc.). System 10 may include at least a support 14 and a print head (“head”) 16. Head 16 may be coupled to and moved by support 14. In the disclosed embodiment of FIG. 1, support 14 is a robotic arm capable of moving head 16 in multiple directions during fabrication of structure 12, such that a resulting longitudinal axis of structure 12 is three-dimensional. It is contemplated, however, that support 14 could alternatively be an overhead gantry or a hybrid gantry/arm also capable of moving head 16 in multiple directions during fabrication of structure 12. Although support 14 is shown as being capable of multi-axis movements, it is contemplated that any other type of support 14 capable of moving head 16 in the same or in a different manner could also be utilized, if desired. In some embodiments, a drive may mechanically couple head 16 to support 14 and may include components that cooperate to move and/or supply power or materials to head 16.

Head 16 may be configured to receive or otherwise contain a matrix. The matrix may include any type of material (e.g., a liquid resin, such as a zero-volatile organic compound resin; a powdered metal; etc.) that is curable. Exemplary matrixes include thermosets, single- or multi-part epoxy resins, polyester resins, cationic epoxies, acrylated epoxies, urethanes, esters, thermoplastics, photopolymers, polyepoxides, thiols, alkenes, thiol-enes, reversible resins (e.g., Triazolinedione, a covalent-adaptable network, a spatioselective reversible resin, etc.) and more. In one embodiment, the matrix inside head 16 may be pressurized, for example by an external device (e.g., an extruder or another type of pump—not shown) that is fluidly connected to head 16 via a corresponding conduit (not shown). In another embodiment, however, the matrix pressure may be generated completely inside of head 16 by a similar type of device. In yet other embodiments, the matrix may be gravity-fed through and/or mixed within head 16. In some instances, the matrix inside head 16 may need to be kept cool and/or dark to inhibit premature curing; while in other instances, the matrix may need to be kept warm for the same reason. In either situation, head 16 may be specially configured (e.g., insulated, chilled, and/or warmed) to provide for these needs.

The matrix may be used to coat, encase, or otherwise at least partially surround any number of continuous reinforcements (e.g., separate fibers, tows, rovings, ribbons, and/or sheets of material) and, together with the reinforcements, make up at least a portion (e.g., a wall) of composite structure 12. The reinforcements may be stored within (e.g., on separate internal spools—not shown) or otherwise passed through head 16 (e.g., fed from external spools). When multiple reinforcements are simultaneously used, the reinforcements may be of the same type and have the same diameter and cross-sectional shape (e.g., circular, square, flat, etc.), or of a different type with different diameters and/or cross-sectional shapes. The reinforcements may include, for example, carbon fibers, vegetable fibers, wood fibers, mineral fibers, glass fibers, metallic wires, optical tubes, etc. It should be noted that the term “reinforcement” is meant to encompass both structural and non-structural types of continuous materials that can be at least partially encased in the matrix discharging from head 16.

The reinforcements may be exposed to (e.g., coated with) the matrix while the reinforcements are inside head 16, while the reinforcements are being passed to head 16 (e.g., as a prepreg material), and/or while the reinforcements are discharging from head 16, as desired. The matrix, dry reinforcements, and/or reinforcements that are already exposed to the matrix (e.g., wetted reinforcements) may be transported into head 16 in any manner apparent to one skilled in the art.

The matrix and reinforcement may be discharged from a nozzle 18 of head 16 via at least two different modes of operation. In a first mode of operation, the matrix and reinforcement are extruded (e.g., pushed under pressure and/or mechanical force) from nozzle 18, as head 16 is moved by support 14 to create the 3-dimensional shape of structure 12. In a second mode of operation, at least the reinforcement is pulled from nozzle 18, such that a tensile stress is created in the reinforcement during discharge. In this mode of operation, the matrix may cling to the reinforcement and thereby also be pulled from nozzle 18 along with the reinforcement, and/or the matrix may be discharged from nozzle 18 under pressure along with the pulled reinforcement. In the second mode of operation, where the matrix is being pulled from nozzle 18, the resulting tension in the reinforcement may increase a strength of structure 12, while also allowing for a greater length of unsupported material to have a straighter trajectory (i.e., the tension may act against the force of gravity to provide free-standing support for structure 12).

The reinforcement may be pulled from nozzle 18 as a result of head 16 moving away from an anchor point 20. In particular, at the start of structure-formation, a length of matrix-impregnated reinforcement may be pulled and/or pushed from nozzle 18, deposited onto anchor point 20, and cured, such that the discharged material adheres to anchor point 20. Thereafter, head 16 may be moved away from anchor point 20, and the relative movement may cause additional reinforcement to be pulled from nozzle 18. It should be noted that the movement of the reinforcement through head 16 could be assisted (e.g., via internal feed mechanisms), if desired. However, the discharge rate of the reinforcement from nozzle 18 may primarily be the result of relative movement between head 16 and anchor point 20, such that tension is created within the reinforcement.

Nozzle 18 may be fluidly connected to a matrix reservoir 22. Although matrix reservoir 22 is shown as being at least partially inside of head 16, it should be noted that matrix reservoir 22 could alternatively be located separately upstream of head 16. As shown in FIG. 2, nozzle 18 may be a generally cylindrical component having an upstream or base end in fluid communication with matrix reservoir 22, a downstream or tip end, and one or more axially oriented passages that extend from the base end to the tip end.

Any number of reinforcements (represented as R in FIG. 2) may be passed axially through reservoir 22 where at least some matrix-wetting occurs (matrix represented as M in FIG. 2), and discharged from head 16 via nozzle 18. One or more orifices 24 may be located at the tip end of nozzle 18 to accommodate passage of the matrix-wetted reinforcements. In the disclosed embodiment, a single generally circular orifice 24 is shown. It is contemplated, however, that multiple circular orifices could be used. In addition, orifices 24 of another shape (e.g., a rectangular shape) may allow for printing of ribbons and/or sheets. In the embodiment of FIG. 2, the single orifice 24 is substantially aligned (e.g., aligned within engineering tolerances) with a central axis of nozzle 18.

Returning to FIG. 1, one or more cure enhancers (e.g., one or more light sources, ultrasonic emitters, lasers, heaters, catalyst dispensers, microwave generators, etc.) 26 may be mounted proximate head 16 (e.g., at a trailing side of nozzle 18) and configured to enhance a cure rate and/or quality of the matrix as it is discharged from nozzle 18. Cure enhancer 26 may be controlled to selectively expose internal and/or external surfaces of structure 12 to energy (e.g., light energy, electromagnetic radiation, vibrations, heat, a chemical catalyst or hardener, etc.) during the formation of structure 12. The energy may increase a rate of chemical reaction occurring within the matrix, sinter the material, harden the material, or otherwise cause the material to cure as it discharges from nozzle 18.

A controller 28 may be provided and communicatively coupled with support 14, head 16, and any number and type of cure enhancers 26. Controller 28 may embody a single processor or multiple processors that include a means for controlling an operation of system 10. Controller 28 may include one or more general- or special-purpose processors or microprocessors. Controller 28 may further include or be associated with a memory for storing data such as, for example, design limits, performance characteristics, operational instructions, matrix characteristics, reinforcement characteristics, characteristics of structure 12, and corresponding parameters of each component of system 10. Various other known circuits may be associated with controller 28, including power supply circuitry, signal-conditioning circuitry, solenoid/motor driver circuitry, communication circuitry, and other appropriate circuitry. Moreover, controller 28 may be capable of communicating with other components of system 10 via wired and/or wireless transmission.

One or more maps may be stored in the memory of controller 28 and used during fabrication of structure 12. Each of these maps may include a collection of data in the form of models, lookup tables, graphs, and/or equations. In the disclosed embodiment, the maps are used by controller 28 to determine desired characteristics of cure enhancers 26, the associated matrix, and/or the associated reinforcements at different locations within structure 12. The characteristics may include, among others, a type, quantity, and/or configuration of reinforcement and/or matrix to be discharged at a particular location within structure 12, and/or an amount, intensity, shape, and/or location of desired curing. Controller 28 may then correlate operation of support 14 (e.g., the location and/or orientation of head 16) and/or the discharge of material from head 16 (a type of material, desired performance of the material, cross-linking requirements of the material, a discharge rate, etc.) with the operation of cure enhancers 26, such that structure 12 is produced in a desired manner.

Templates may sometimes be used during structure fabrication to determine the location of features to be added, material to be removed, surfaces to be treated, etc. In some applications, the templates are physical patterns having precisely located openings that are carefully placed over a base structure to guide a desired post-fabrication process. In other applications, the templates are virtual patterns projected onto the base structure. By continually using the same template, accuracy and repeatability in fabrication can be achieved.

Although suitable for some applications, conventional templates can also be expensive and difficult to use. For example, conventional templates must be continuously updated to reflect ongoing changes to the structure, and physical templates can wear, warp, or be damaged. And while virtual templates may be less prone to wear, warpage, and damage, the systems required to accurately project the virtual templates can be expensive, complex, and difficult to control.

Other arrangements for creating fabrication templates using head 16 are shown in FIGS. 2-4. For example, FIG. 2 shows head 16 as having a base matrix source 30, and any number of tint sources (e.g., 32, 34, 36). Tint sources 32-36 may include, for example, valves, jets, and/or spray nozzles that are configured to supply differently tinted matrixes or only tint into matrix reservoir 22 and/or nozzle 18 at select times and/or in association with the position of nozzle 18 at select locations (intended drill holes, tap locations, surfaces to be roughed or smoothed, weld locations, etc.) on structure 12 (referring to FIG. 4). With this configuration, sources 30-36 may be selectively turned on/off to discharge a desired amount of matrix tinted with a specific color at a particular location corresponding to a required post-process (e.g., drilling, grinding, welding, bonding, assembly, etc.) to be performed at that location. Because support 14 (referring to FIG. 1) may already include the actuators, controls, sensors, feedback, processors, etc. necessary to precisely locate head 16 during normal material discharge, additional template-specific control components (e.g., other than sources 32-36) may not be required.

Head 16 of FIG. 4 may provide similar template functionality, but in a slightly different manner. For example, head 16 of FIG. 4 may include external tint sources 32-36. These sources may be mounted, for instance, at a trailing side of head 16 and/or to an arm (not shown) that trails behind head 16. These sources may includes jets or spray nozzles that are controlled to selectively spray the tint or tinted matrix onto the composite material discharging from nozzle 18, before and/or after being exposed to cure energy by cure enhancers 26. It is contemplated that a combination of internal and external tint sources could be utilized with a common head 16, if desired.

It should be noted that tint sources 32-36 may be used for purposes other than or in addition to templating, if desired. For example, any one or more of sources 32-36 may be used for aesthetic purposes and/or to apply a desired surface finish or treatment to particular locations of structure 12. It should be noted that the tinting provided by sources 32-36 may be internal (e.g., provided at an intermediate layer) or external to structure 12.

It is contemplated that, for either embodiment of FIGS. 2 and 3, the tint or tinted matrix from each source 32-36 could be used independently to provide for three separate colors, or selectively mixed to provide for any number of additional color shades. For example, sources 32-36 could be associated with red, green, and blue or cyan, magenta, and yellow; and black, or with another color swatch. Different amounts of tint or tinted matrixes from two or more sources could then be selectively mixed together, applied in overlapping layers, or otherwise combined to produce any desired color within or on structure 12. It is also contemplated that in addition to or instead of dispensing a tint or tinted matrix, one or more of sources 32-36 could dispense an additive (e.g., glass powder that causes shimmering, glow-in-the-dark chemicals, etc.) that changes an appearance, but not necessarily a color, of structure 12. Further, it is contemplated that the tints, tinted matrixes, and/or additives could be fiber-dependent, if desired. For example, when a particular fiber is passing through head 16, controller 28 may cause a particular color and/or additive to be used with that particular fibers to produce a unique effect. And when another fiber is passing through head 16, controller 28 may cause a different color and/or additive to be used with the other fiber.

INDUSTRIAL APPLICABILITY

The disclosed system and print head may be used to continuously manufacture composite structures having any desired cross-sectional size, shape, length, density, and/or strength. The composite structures may include any number of different reinforcements of the same or different types, diameters, shapes, configurations, and consists, each coated with a common matrix. In addition, the disclosed print head may allow for efficient templating that can be used during later processing events. Operation of system 10 will now be described in detail.

At a start of a manufacturing event, information regarding a desired structure 12 may be loaded into system 10 (e.g., into controller 28 that is responsible for regulating operations of support 14 and/or head 16). This information may include, among other things, a size (e.g., diameter, wall thickness, length, etc.), a contour (e.g., a trajectory), surface features (e.g., ridge size, location, thickness, length; flange size, location, thickness, length; etc.) and finishes, connection geometry (e.g., locations and sizes of couplings, tees, splices, etc.), location-specific matrix stipulations, location-specific reinforcement stipulations, etc. It should be noted that this information may alternatively or additionally be loaded into system 10 at different times and/or continuously during the manufacturing event, if desired. Based on the component information, one or more different reinforcements and/or matrixes may be selectively installed and/or continuously supplied into system 10.

Installation of the reinforcements may be performed by passing the reinforcements down through matrix reservoir 22, and then threading the reinforcements through nozzle 18. Installation of the matrix may include filling reservoir 22 within head 16 and/or coupling of an extruder or external bath (not shown) to head 16. Head 16 may then be moved by support 14 under the regulation of controller 28 to cause matrix-coated reinforcements to be placed against or on a corresponding stationary anchor point 20. Cure enhancers 26 within head 16 may then be selectively activated to cause hardening of the matrix surrounding the reinforcements, thereby bonding the reinforcements to anchor point 20.

The component information may then be used to control operation of system 10. For example, the reinforcements may be pulled and/or pushed from nozzle 18 (along with the matrix), while support 14 selectively moves head 16 in a desired manner during curing, such that an axis of the resulting structure 12 follows a desired trajectory (e.g., a free-space, unsupported, 3-D trajectory). Once structure 12 has grown to a desired size and/or length, structure 12 may be disconnected (e.g., severed) from head 16 in any desired manner.

At any time during operation of system 10, one or more of sources 30-36 may be active alone or together to apply tint to structure 12. In one embodiment, the tint is mixed with the matrix inside of head 16, such that all of the material subsequently discharging from nozzle 18 may be have a desired appearance. In other embodiment, the tint may only be sprayed onto the material discharging from head 16. In either situation, the tint may mark an area of structure 12 at which post-processing should occur. Alternatively or additionally, the tint may be used simply for aesthetic purposes. The tint may be applied at an outer layer or between layers. The activation of sources 30-36 may be coordinated with movements of head 16 and a known location of nozzle 18, such that the tint is applied precisely.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system and head. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed system and head. For example, it is contemplated that one or more of the tints added to the matrix material discharging from the disclosed print head and/or applied to the discharging material may be generally transparent to the human eye. In this situation, the tint may only be visible via a machine sensor or camera. For instance, the tint may be radioactive, luminescent, magnetic, etc. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents. 

What is claimed is:
 1. A print head for an additive manufacturing system, comprising: a nozzle configured to discharge a composite material; and a source of tint configured to apply the tint to the composite material.
 2. The print head of claim 1, further including a matrix reservoir located upstream of the nozzle, wherein the source of tint is located inside of the matrix reservoir.
 3. The print head of claim 2, wherein the source of tint is one of a valve, a jet, and a spray nozzle.
 4. The print head of claim 3, wherein: the composite material includes a reinforcement at least partially coated in a matrix; and the source of tint is configured to supply tinted matrix to the print head.
 5. The print head of claim 4, wherein: the matrix is a curable resin; and the print head further includes a cure enhancer configured to expose the composite material to a cure energy after discharge from the nozzle.
 6. The print head of claim 3, wherein the source of tint includes a plurality of jets configured to selectively direct different colors of tint into the matrix reservoir.
 7. The print head of claim 1, wherein the source of tint is mounted at a trailing side of the nozzle to tint the composite material after discharge from the nozzle.
 8. The print head of claim 7, wherein the source of tint includes a plurality of jets configured to selectively direct different colors of tint onto the composite material.
 9. The print head of claim 8, wherein: the composite material includes a reinforcement at least partially coated in a matrix; the matrix is a curable resin; and the print head further includes a cure enhancer configured to expose the composite material to a cure energy after discharge from the nozzle and after the tint is on the composite material.
 10. The print head of claim 8, wherein: the composite material includes a reinforcement at least partially coated in a matrix; the matrix is a curable resin; and the print head further includes a cure enhancer configured to expose the composite material to a cure energy after discharge from the nozzle and before the tint is on the composite material.
 11. A print head for an additive manufacturing system, comprising: a matrix reservoir; a nozzle fluidly connected to the matrix reservoir and configured to discharge a composite material including a reinforcement at least partially coated in a matrix from the matrix reservoir; a cure enhancer mounted at a trailing side of the nozzle and configured to expose the matrix to a cure energy after discharge from the nozzle; and a source of tint mounted at a trailing side of the nozzle to tint the composite material after discharge from the nozzle.
 12. The print head of claim 11, wherein the source of tint is one of a valve, a jet, and a spray nozzle.
 13. The print head of claim 11, wherein the source of tint includes a plurality of jets configured to selectively direct different colors of tint onto the composite material.
 14. The print head of claim 11, wherein the cure enhancer is configured to expose the composite material to the cure energy after the tint is on the composite material.
 15. The print head of claim 11, wherein the cure enhancer is configured to expose the composite material to the cure energy before the tint is on the composite material.
 16. An additive manufacturing system, comprising: a moveable support; a print head connected to the moveable support and configured to discharge a composite material including a continuous reinforcement that is at least partially coated with a matrix, the print head including: a matrix reservoir; a nozzle configured to discharge a composite material; a source of tint configured to apply the tint to the composite material; and a cure enhancer configured to expose the composite material to a cure energy after discharge from the nozzle; a controller configured to coordinate operation of the moveable support with activation of the source of tint and the cure enhancer.
 17. The additive manufacturing system of claim 16, wherein the source of tint is one of a valve, a jet, and a spray nozzle located inside of the matrix reservoir.
 18. The additive manufacturing system of claim 16, wherein the source of tint is mounted at a trailing side of the nozzle to tint the composite material after discharge from the nozzle.
 19. The additive manufacturing system of claim 16, wherein the source of tint is one of a valve, a jet, and a spray nozzle.
 20. The additive manufacturing system of claim 16, wherein the source of tint includes a plurality of jets configured to selectively direct different colors of tint onto the composite material. 